Writing Supplements That Get Approved the First Time: A Playbook for MPI and SGI Shops

Key findings

1. 1Supplements average 25-35% of total claim dollars on Canadian collision repairs, and rejected or reworked supplements are a top driver of keys-to-keys delay.
2. 2Under the MPI Light Vehicle Tariff, supplements must reference an authorized repair plan line, a teardown discovery, or a published OEM procedure - 'shop opinion' is not approvable.
3. 3First-time supplement approval rates of 85% or higher correlate with shops that capture photographic evidence and OEM procedure citations at the moment the supplement is written, not after rejection.
4. 4The most common rejection reasons on MPI and SGI supplements are missing teardown photos, no OEM procedure citation for calibrations and welds, and labour line items that duplicate the original write-up.
5. 5Documentation-first shops report 40-60% fewer supplement re-submissions and 1.5-2.5 fewer keys-to-keys days per claim than peers writing supplements reactively.

Body

1. What a supplement actually is on an MPI or SGI claim

A supplement on an MPI or SGI claim is a formal amendment to an authorized repair plan that adds, removes, or changes line items based on findings discovered after the original estimate was approved. It is not a correction of estimator error and not a place to add work the shop forgot to write the first time. The Light Vehicle Tariff (LVT) on Manitoba Public Insurance claims and the SGI Accredited Repair program both treat the original write-up as the contract; the supplement is how that contract is renegotiated when the vehicle reveals damage that was not visible at FNOL or write-up.

Every supplement line lives on a spectrum of defensibility. At one end: a hidden structural fracture revealed at teardown, photographed, and tied to an OEM sectioning procedure - this is approvable on the first read. At the other end: an added 0.5 hour of refinish labour with no photo, no procedure, and no note explaining why the original line was insufficient - this gets rejected, returned, and adds two days to cycle time.

2. The mechanics: what MPI and SGI require on every supplement line

Both MPI and SGI require a supplement line to answer three questions before it is approvable: what was found, how it was found, and what the published procedure requires. The Mitchell Connect platform (used on MPI claims) and the estimating workflow on SGI Accredited Repair claims both have fields for notes and image attachments precisely because the carrier expects each line to be self-documenting. A supplement that requires the appraiser to call the shop for context is, by definition, not first-time approvable.

On MPI claims specifically, the LVT publishes labour rates, included operations, and not-included operations for most repair categories. A supplement line that bills for an operation already included in the original line under the LVT will be rejected on procedural grounds alone - the appraiser does not have to evaluate the merit. SGI's Accredited Repair program uses a parallel logic: included operations under the program guidelines cannot be billed twice.

3. The teardown discipline that separates first-time approvals from rework

Shops with the highest first-time supplement approval rates run a structured teardown before writing any supplement, and they document the teardown as if the appraiser were standing in the bay. The discipline has three parts: a written teardown plan tied to the original estimate, photographic capture at each disassembly step, and a same-day blueprint review before the supplement is submitted. Shops that skip the blueprint step and write supplements piecemeal as parts come off see rejection rates 2-3 times higher than shops that batch their findings.

4. ADAS, calibrations, and OEM procedures - the highest-rejection supplement category

ADAS calibration line items are the single most-rejected supplement category on MPI and SGI claims, and almost always for the same reason: the shop billed a calibration without citing the OEM trigger that requires it. Both MPI and SGI accept OEM position statements as authoritative; what they do not accept is a calibration line with no procedure attached. A 2024 review of Canadian insurer DRP scorecards showed calibration-related supplement rejections accounted for 18-24% of all returned supplement lines, even though calibrations were a single-digit percentage of total line count.

The defensible pattern for a calibration supplement: cite the OEM service information section number, attach the trigger language verbatim (for example, 'front camera calibration required after windshield replacement'), include the pre-scan and post-scan reports, and document the calibration target setup with photos. A calibration line built this way is approvable on the first read because it leaves the appraiser nothing to question.

5. Where shops typically lose ground on supplement approval

The pattern of supplement rejection on MPI and SGI claims is consistent enough to map. Most lost ground does not come from carriers being difficult - it comes from preventable documentation gaps that the shop could close at write-up or teardown without changing carrier rules.

• Writing supplements piecemeal as parts come off the vehicle, leading to three or four submissions when one would have been approved.
• Submitting a supplement before teardown is complete, then re-submitting when more damage is found - each re-submission resets the appraiser's review queue.
• Billing operations already included in the LVT or SGI program tariff under the original line, with no awareness of the carrier's included-operation list.
• Adding refinish or labour time without documenting why the original allowance was insufficient.
• Citing 'OEM procedure' without attaching the procedure document or section reference.
• Skipping the pre-scan and post-scan reports on calibrations, then billing the calibration line.
• Not photographing the teardown progression - only the final state - which leaves the appraiser unable to verify cause.

6. How RocketPros aligns to first-time supplement approval

RocketPros runs alongside Mitchell Connect on MPI claims and the shop's existing estimating platform on SGI Accredited Repair claims, surfacing estimate-completeness signals at write-up and supplement time so the documentation that MPI and SGI require is captured before submission, not after rejection. RocketPros does not replace the LVT, the SGI program guidelines, or any OEM procedure - those remain the source of truth. What it does is make compliance with those rules mechanical: when a line item triggers an OEM calibration requirement, RocketPros surfaces the trigger; when a supplement line duplicates an LVT-included operation, it flags the duplication before submission.

The result is fewer supplement re-submissions, a shorter gap between supplement write and supplement approval, and a per-VIN documentation trail that holds up under DRP scorecard review. RocketPros reports claim-level metrics back to the shop - first-time approval rate by line category, average days from supplement submission to approval, supplement frequency per claim - so shop managers can see which estimators and which damage categories are driving rework before it shows up on the carrier scorecard.

7. The carrier perspective: why first-time approval matters to MPI and SGI

From the MPI and SGI program-management view, supplement rework is one of the largest hidden cost drivers in the claims process. Each rejected supplement consumes appraiser time, extends rental days, delays customer return, and adds friction to the relationship with the accredited shop. Carriers do not benefit from rejecting supplements - they benefit from approving correct supplements quickly and rejecting the small number that genuinely fall outside the program.

MPI and SGI both reward shops that submit complete, well-documented supplements through scorecard placement, faster authorization, and continued program standing. The carrier's published rules - the LVT, the SGI Accredited Repair guidelines, OEM position statements they recognize - are the source of truth, and shops that build their write-up and teardown discipline around those rules earn the operational benefits that follow.

8. A practical first-time-approval checklist for every supplement

1. 1Complete teardown before writing the supplement - one consolidated submission beats three partial ones.
2. 2Photograph each disassembly step, not just the final state.
3. 3For every line, name the cause, the discovery method, and the procedure or LVT reference.
4. 4For every calibration, cite the OEM trigger language verbatim and attach pre/post-scan reports.
5. 5Cross-check each line against the LVT or SGI program included-operations list before submission.
6. 6Attach OEM procedure print-outs or section references for any sectioning, welding, or bonding operation.
7. 7Submit the supplement with a single consolidated note that walks the appraiser through the findings in the same order as the photos.

Frequently asked

Citations

1. [1]Manitoba Public Insurance - Body Shop & Glass Information portal (program documents, Light Vehicle Tariff, accreditation framework, supplement bulletins).https://www.mpi.mb.ca/
2. [2]Saskatchewan Government Insurance - Accredited Repair program guidelines and shop information for SGI claims.https://www.sgi.sk.ca/
3. [3]Insurance Bureau of Canada - industry data on auto insurance claims, repair costs, and provincial program structure.https://www.ibc.ca/
4. [4]Canadian Collision Industry Forum (CCIF) - industry events and working group output on estimating, OEM procedures, and DRP performance.https://ccif.ca/
5. [5]Statistics Canada, Consumer Price Index - vehicle parts, maintenance and repairs (Table 18-10-0004-01).https://www150.statcan.gc.ca
6. [6]CCC Intelligent Solutions, Crash Course Report, 2024 Edition - North American repairable severity, supplement frequency, and cycle time benchmarks.https://cccis.com
7. [7]Mitchell International, Industry Trends Report - quarterly data on collision severity, supplement patterns, and ADAS line frequency.https://www.mitchell.com/insights
8. [8]Society of Collision Repair Specialists (SCRS) - guidance on documentation, OEM procedure adherence, and not-included operations.https://www.scrs.com
9. [9]I-CAR Repairability Technical Support (RTS) portal - OEM repair procedure access and position statements recognized across Canadian and US carriers.https://rts.i-car.com
10. [10]Insurance Institute for Highway Safety / Highway Loss Data Institute (IIHS-HLDI) - claim severity data and ADAS-related repair cost trends.https://www.iihs.org
11. [11]Repairer Driven News - ongoing coverage of supplement disputes, OEM position statements, and DRP program changes in North America.https://www.repairerdrivennews.com
12. [12]Automotive Service Association (ASA) - shop-side guidance on documentation, OEM procedure billing, and insurer relations.https://asashop.org

What this looks like inside RocketPros

The audit logic, scoring, and documentation patterns in this paper map directly to four RocketPros modules. If you want this applied to your shop's real estimates, start with the module that fits the workflow you're trying to fix.

• RPS ComplianceTrack MPI, SGI, and DRP program risk before it affects scorecards.
• Estimate AnalysisCatch missed labor, materials, parts, and documentation gaps before submission.
• AutomationRead saved Mitchell, CCC, and Audatex files without manual upload.
• ADAS CalibrationSurface calibration triggers tied to sensors and OEM procedures.

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